Energized anode assembly



Aug. 1, 1961 Original Filed Dec. 28, 1956 FIG. I.

5 Sheets-Sheet l \9 2O 2O 2O r I 9 1s 20 ll-m ll lll2 l2 -42 l2 3 ANODEBALANCING CONTROL AND METER BOX I80 Low Voltage Rectifier Low VoltageADJUSTABLE A.C. A C TRANSFORMER Input l7b v INVENTOR HERMAN S. PREISERFRANK E. COOK BORIS H. TYTELL BY L ATTORNEY Aug. 1, 1961 H. s. PREISERETAL ENERGIZED ANODE. ASSEMBLY Original F led D90. 28, 1956 5Sheets-Sheet 2 INVENTOR HERMAN S. PREISER FRANK E. COOK BORIS H. TYTELL.

ATTORNEY Aug. 1, 1961 H. S. PREISER ET AL ENERGIZED ANODE ASSEMBLYOriginal ile D80. 28, 1956 FIG. 6.

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INVENTOR HERMAN S. PREISER FRANK E. COOK BORIS H. TYTELL ATTORNEY UnitedStates Patent 2,994,658 ENERGIZED ANODE ASSEMBLY Herman S. Preiser,Springfield, and Frank E. Cook, Arlington, Va., and Boris H. Tytell,Mattapan, Mass. Original application Dec. 28, 1956, Ser. No. 631,377,

now Patent No. 2,910,419, dated Oct. 27, 1959. Divided and thisapplication May 29, 1959, Ser. No.

6 Claims. (Cl. 204-196) (Granted under Title 35, U8. Code (1952), sec.266) The invention described herein may be manufactured and used by orfor the Government of the United States for governmental purposeswithout the payment of any royalties thereon or therefor.

This application is a division of applicants copending applicationSerial No. 631,377, filed December 28, 1956, now Patent No. 2,910,419,October 27, 1959, for Energized Anode Holder Assembly.

This invention relates to cathodic protection of metals againstcolrosion, and more particularly to cathodic protection of theunderwater hull of a surface vessel, submarine or the like againstcorrosion.

Cathodic protection techniques for corrosion control of marinestructures are gradually finding widespread acceptance in marine andnaval fields. Briefly stated, cathodic protection is the use of animpressed direct current for reducing or suppressing electrochemicalcorrosion of a metallic structure immersed in an electrolyte by makingthe structure a cathode for the impressed current. The impressed currentmay be supplied by sacrificial galvanic anodes or by electricallyenergized anodes. This invention is primarily concerned with the lattersystem employing inert anode materials.

For a complete disclosure of the factors responsible for the corrosionof the underwater hull of a ship or like structure reference may be hadto applicants above copending application Serial No. 631,377, now PatentNo. 2,910,419, October 27, 1959.

From an examination of the factors responsible for the corrosion of theunderwater hull of a ship, applicants concluded that specific materialsare needed for use in cathodic protection systems. The particularproperties sought will depend on the end use of the material. Ingeneral, materials are needed which are nonconducting, alkali resistant,oxy-chloride resistant, have low permeability to water transmissionunder a potential gradient, low water absorptivity, are nonreactive tosea water, have high strength, are impact resistant and are readilyformed into a variety of shapes. Plastic materials because of theirversatility lend themselves admirably for components of cathodicprotection systems. The instant application is concerned with theutilization of plastics, ceramics and other acid and alkali resistant,dielectric materials.

Briefly, the elements of a cathodic protection system consist of ananode; a cathode; a current source and external circuit; and measuringinstruments.

The anode for impressed current systems may be a platinum-clad silver orcopper rod, or an integral platinum or platinum-clad disc or gauze, agraphite rod or slab, or other shapes of inert materials such as lead,and leadalloys and high silicon iron alloys. The anode must be mountedin suitable holders which must be dielectric, oxy-chloride resistant,and rugged.

The cathode of a cathodic protection system is the structure underconsideration; in the instant case a ships hull. In order to insureadequate current distribution from the anode, shield materials aremounted on the hull in the vicinity of the anode. These materials mustadhere to steel, have low permeability to electro-osmosis, have alkaliresistance, be tough and flexible, and have good dielectric properties.

Patented Aug. 1, 1961 "ice The current source and external circuitimplies the use of chemically resistant cable sheaths and suitable cableattachment to the anode with appropiate seals.

The measuring instrument used for determining the cathodic potential ofthe structure is the reference electrode. This sensitive element must behoused in a dielectric, nonreactive, streamlined casing which is fittedwith suitable cable seals.

The instant invention is particularly concerned with holders forattaching and supporting rod-type, rectifier energized anodes on thehull of a ship; surface or submarine.

An object of this invention is to provide an improved anode holder foruse in cathodic protection systems.

Another object of the invent-ion is to provide a streamlined anodeholder.

Another object of the invention is to provide an anode holder that isdielectric.

Another object of the invention is to provide an anode holder that isresistant to alkali reactions.

Another object of the invention is to provide an anode holder that isresistant to oxy-chloride reactions.

Another object of the invention is to provide an anode holder that islight in weight, low in cost and high in mechanical strength.

Another object of the invention is to provide an anode holder whereinall mounting hardware is insulated and isolated.

A further object of the invention is to provide an anode holder whichassists in the distribution of current from the anode.

A further object of the invention is to provide an anode holder whichprovides relatively free and rapid circulation of an electrolyte betweenthe anode and a cathode.

In the instant embodiment of the invention, the holder for aplatinum-clad, rod anode is constructed of steel with a ceramic coating,such as porcelain enamel, on all exposed surfaces and wherein the anodeis supported in the holder by a plurality of tet-rafluoroethylene,Teflon, discs.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawings in which like referencenumerals designate like parts throughout the several views thereof, andwherein:

FIG. 1 shows a schematic wiring diagram for an impressed currentcathodic protection system in accordance with this invention;

FIG. 2 is a side elevation of a holder for a platinumclad rod anode inaccordance with the instant invention;

FIG. 3 is a top plan view of the holder shown in FIG. 2;

FIGS. 4, 5 and 6 are enlarged transverse sections taken on lines 4-4, 55and 66, respectively, of FIG. 2;

FIG. 7 is an enlarged exploded perspective of a clamp shown in FIGS.2-6;

FIG. 8 is an enlarged perspective of one of a plurality ofanode-supporting discs shown in broken lines in FIG. 2; and

FIG. 9 is an enlarged perspective, partly in section, of a disc forsupporting the extreme right hand end of the anode as viewed in FIG. 2.

Referring first to FIG. 1, which illustrates a cathodic protectionsystem wherein an impressed current is sup plied by rectifier energizedanodes, the numeral 10 designates the hull of a surface ship protectedby a plurality of anodes 20 spaced around the sides and stem thereof. Aspointed out in detail hereinafter, each of the anodes is shielded fromthe hull by a dielectric shield or blanket 11. Each of the anodes isconnected by a conductor 12 to an anode balancing control and meter box13, which purpose is for measuring current output of each anode and forbalancing differences in line resistance. Control 13 is connected by aconductor 14 to the positive side of a low voltage rectifier 15, whilethe negative side of the rectifier is grounded to the hull of the vesselby a conductor 16, thereby making the hull the cathode of the lowvoltage circuit. A pair of conductors 17a and 17b connect opposite sidesof the rectifier to the low voltage A.C. output of electrical energyfrom an adjustable transformer 18 which is fed by an A.C. input 18a.Reference electrodes 19 are suitably mounted on the hull at leasttwenty-five feet from the nearest anode and are connected to a suitablepotentiometer, not shown, for determining the polarization of the hull.Based on readings taken by the reference electrodes, adjustment can bemade in the transformer '18 to change the current output to the anodesto correspond to the proper value. Reference electrodes (Ag-AgCl)readings below -.80 volt require an increase in the anode current, andreadings above .80 volt require a decrease in the anode current. Theelectric circuits, illustrated in FIG. 1, are not per se a part of thisinvention and therefore need not be described in further detail. Itbeing suflicient to state that by these circuits a controlled lowvoltage current flows from the rectifier to the several anodes and fromthese through the sea water to the hull and back to the rectifier.

Referring now to FIGS. 26, in accordance with the instant invention, theanode assembly, indicated generally by reference numeral 20, includes aholder 21 for supporting an inert, rod anode 22. The holder is formed asa built-up, inverted T-shaped assembly of open hearth iron platescovered with a ceramic coating, such as, an acid resistant, dielectricporcelain enamel. The holder 21 can also be constructed from an integralrolled T-bar metal section or a built-up plastic section. The anode isformed of a platinum-clad silver rod. Between the base of the holder andthe hull 10 of the vessel is a thick rubber pad 23 (FIGS. 4-6) and thedielectric shield 11. The rubber pad, which is of substantially the samehorizontal contour as the base of the holder, insures proper fit of theholder over minor irregularities in the hull and it provides a :measureof shock and vibration protection to the holder. The dielectric shieldis formed of sheet neoprene and it stabilizes and extends the currentpaths.

In practicing the invention, with an anode assembly measuring 1' x aneoprene dielectric shield measuring 6' x x /8" thick gives excellentresults in forcing anode currents out from the anode into surroundingsea water where resistance paths are more nearly uniform, resulting insubstantially uniform distribution of anode currents over the hull ofthe vessel. This effectively reduces high current concentration near theanode with its deleterious elfects on existing paint coatings. Inpractice, the effectiveness of the shield may be enhanced by applying aheavy coat of vinyl paint 2 to 3 feet out from the edges of the neoprenesheet. The manner of attaching the shield to the hull is described indetail in applicants parent application, Serial No. 631,377, referred tohereinbefore.

With reference to FIGS. 46, the holder 21 includes a base plate 25 towhich is welded an upright plate 26. A plurality of clamp plates 27 arespaced along the upright plate (FIG. 2) and welded thereto, as shown inFIG. 5. A plurality of companion clamp plates 28 are attached torespective clamp plates 27 by screws 29. So that the heads of the screwsare flush with the outer vertical surface of plates 28, these plates arecounlersunk to receive the heads of the screws, while the shank of thescrews pass through holes in the upright plate 26 and are screw threadedinto tapped holes in clamp plates 27.

Each of the clamp plates of the two sets is provided with ofisetportions so as to fit upon the upright plate and with a circular recessto receive and clamp therebetween an anode-holding disc 30. The discs 30are formed of insulating plastic, such as Teflon, with right hand en d30a (FIG. 2) formed as shown in FIG. 9, with a radial bore or well 31aextending part Way thereinto to receive the right hand end of the rodanode, and with a saw out 3211 extending into the disc from the upperouter surface thereof to the longitudinal axis of the well. Each of thediscs 30 is formed as shown in FIG. 8 with a diametric bore 31 extendingtherethrough and with a saw cut 32 extending through one half of thedisc to meet the bore 31. As shown in FIG. 2, the upright plate 26 ofthe holder 21 is formed with an elongated slot or opening 26a for thereception of the rod anode 22 and its supporting discs 30 and 39a. Theslot 26a is closed at the right end (FIG. 2) of the holder, and at itsleft end, the slot extends downward for passage of the anode through thehull of the vessel for connection with a low voltage source of current,such as shown in FIG. 1.

In fabricating the inverted T-shaped holder, the upright plate 26, withthe slot 26a formed therein and with the ends beveled for streamliningas shown in FIG. 2, is welded along its length to the base plate 25,then the clamp plates 27 are welded to the upright plate. The welds arethen ground smooth in the manner shown in FIG. 5, and the sub-assemblyof base plate, upright and the one set of clamp plates is coated firstwith a ground coat of porcelain enamel and then with a second or finishcoat of acid resistant, electrical insulating porcelain enamel and thenwith a second or finish coat of acid resistant, electrical insulatingporcelain enamel. The companion clamp plates 28 are likewise coated withtwo coats of porcelain enamel. Then with the discs 30 and 30a positionedon the rod anode, the anode is located in the slot 26a, the discs arelocated within the recesses of the clamp members and the screws 29 areapplied to the clamp members. Prior to the application of the screws tothe clamp members, a pair of plastic Teflon sealing gaskets 34 islocated between the mating surfaces of each of the clamps 28 with theupright plate 26 as shown in FIG. 5. After the gaskets are in place andthe screws tightened, the exposed ends of the screws are covered with aplastic coating of waterproof, dielectric material. The anode assemblyis now ready to be attached to the hull of the vessel.

The anode assembly is attached to the hull by a plurality of corrosionresistant studs 35 (FIG. 6) welded in predetermined spaced relationalong the hull. As shown in FIG. 6, the base plate 25 of the holderassembly is formed with a plurality of openings, spaced in accordancewith the spacing of the studs 35. With the base plate positioned on thestuds, a ferrule 36, formed of epoxy glass laminate or other suitableplastic, is fitted between the stud and the base plate, afterwhich aplastic washer 37a, a standard metal washer 37b and a stop nut 38 areeach applied to each of the studs. After the stop nuts have beenproperly tightened, the fastening assemblies are each capped with aplastic bonnet 39, which bonnet is cemented to the assembly by awaterproof dielectric adhesive. For clarity of illustration, the bonnetshave been omitted in FIG. 2. Thus, the entire anode assembly with theexception of the platinum-clad anode, is waterproofed, is electricallyshielded and insulated from the hull and ambient sea water, and theplatinumclad anode is electrically insulated from the entire holder andelectrically shielded from the immediately surrounding hull, with lowvoltage currents passing only from the platinum-clad anode throughambient sea water to the hull beyond the confines of the dielectricshield 11.

It should be understood, of course, that the foregoing disclosurerelates to only a preferred embodiment of the invention and, althoughthe invention has been illustrated and described in connection withparticular details of construction and the particular materials specificto the instant embodiment of the invention, the details of constructionand the particular materials may be modified and/or interchanged withoutdeparting from the spirit and scope of the invention as set forth in theappended claims.

What is claimed is:

1. An anode assembly for use in impressed current cathodic protectionsystems for under Water protection of the hulls of ships and thelikecomprising, an inert anode, said anode 'being formed of aplatinum-clad rod, a holder for the anode, said holder being formed ofdielectric, anticorrosive, chemically resistant material, said holder'being substantially in the shape of an inverted T and having a baseportion thereof for attachment to the hull and an upright portion formounting the anode in spaced relation to the hull, means for insulatedlymounting the base portion of the holder on the hull, and dielectric,anticorrosive, chemically resistant means for rnounting the anode on theupright portion of the holder in spaced relation to the hull.

2. An anode assembly as set forth in claim 1 wherein the dielectric,anticorrosive and chemically resistant material of the anode holdercomprises a ceramic coating.

3. An anode assembly as set forth in claim 1 wherein the anode holdercomprises a porcelain enameled member and wherein the means for mountingthe anode on the holder includes a plurality of plastic resin discsspaced along the length of the holder and having openings therein forreceiving the anode rod and means on the holder for clamping the discsto the upright portion of the holder and for clamping the discs to theanode rod.

4. An anode assembly for use in impressed current cathodic protectionsystems for under water protection of the hulls of ships and the likecomprising, an inert anode, said anode being formed of a platinum-cladrod, a holder for the anode, said holder being formed of dielectric,anticorrosive, chemically resistant material, said holder beingsubstantially in the shape of an inverted T and having a base portionthereof for attachment to the hull, and an upright portion for mountingthe anode in spaced relation to the hull, said upright portion having anelongated slot formed therein, said anode being mounted within said slotand extending therealong; dielectric, anticorrosive, chemicallyresistant means for mounting the anode within the elongated slot in theupright portion of the holder in spaced relation with the hull, andmeans for insulatedly mounting the base portion of the holder on thehull.

5. An anode assembly as set forth in claim 4 wherein the dielectric,anticorrosive, and chemically resistant material of the holder comprisesa ceramic coating.

6. An anode assembly as set forth in claim 4 wherein the anode holdercomprises a porcelain enameled member and wherein the means for mountingthe anode within the slot in said holder includes a plurality of plasticresin discs spaced along the length of the upright portion of the holderand having openings therein for receiving the anode rod, and means onthe holder for clamping the discs to the upright portion of the holderand for clamping the discs to the anode rod.

References Cited in the file of this patent UNITED STATES PATENTS

1. AN ANODE ASSEMBLY FOR USE IN IMPRESSED CURRENT CATHODIC PROTECTIONSYSTEMS FOR UNDER WATER PROTECTION OF THE HULLS OF SHIPS AND THE LIKECOMPRISING, AN INERT ANODE, SAID ANODE BEING FORMED OF A PLATINUM-CLADROD, A HOLDER FOR THE ANODE, SAID HOLDER BEING FORMED OF DIELECTRIC,ANTICORROSIVE, CHEMICALLY RESISTANT MATERIAL, SAID HOLDER BEINGSUBSTANTIALLY IN THE SHAPE OF AN INVERTED T AND HAVING A BASE PORTIONTHEREOF FOR ATTACHMENT TO THE HULL AND AN UPRIGHT PORTION FOR MOUNTINGTHE ANODE IN SPACED RELATION TO THE HULL, MEANS FOR INSULATEDLY MOUNTINGTHE BASE PORTION OF THE HOLDER ON THE HULL, AND DIELECTRIC,ANTICORROSIVE, CHEMICALLY RESISTANT MEANS FOR MOUNTING THE ANODE ON THEUPRIGHT PORTION OF THE HOLDER IN SPACED RELATION TO THE HULL.